This invention relates to a novel clutch engaging and disengaging means which is used in conjunction with a mechanically operated double clutch mechanism of the type in which a movable clutch member is displaced axially from a neutral position into a first or second direction selectively for effecting a first or second engagement of the clutch resulting in an operative connection of one power transmitting member to another first or second power transmitting member and in which once the clutch has been engaged said movable clutch member is forced to displace into a direction of engaging the clutch by the torque transmitted by such clutch. More particularly, the present invention relates to a novel clutch engaging and disengaging means comprising a control level which is rotated by push-pull control means to displace said movable clutch member in a clutch mechanism of the above described type and which is retained in its neutral position by a spring-biased detent means.
A clutch of the above described type is suitably used in, for example, a marine propulsion device for transmitting power of engine to a propeller shaft selectively into forward or backward direction of marine propulsion. In a clutch of this type, when the clutch has once been engaged the movable clutch member is forced into a direction of engaging the clutch by free-wheel action or servo-action with a pressure corresponding to the torque transmitted by the clutch. A clutch of this type has, therefore, an advantage that efficiency of torque transmission is high and another advantage that the clutch may be engaged with a small operating force so far as the clutch is operated to engage within a small torque range. Clutches of this type may thus be controlled by a remote control and, in practise, are controlled generally by a remote control. In general, such remote control is carried out by a single remote control lever in association with throttle control of an engine which constitutes a source of power to be transmitted by the clutch. Remote control system for such remote control is, in general, fashioned as disclosed in, for example, U.S. Pat. No. 3,043,159 such that fuel supply to the engine is reduced to keep the engine idling during a clutch-engaging operation of displacing the remote control lever from a neutral position into one or another direction and such fuel supply is increased, after the clutch has been engaged, by displacing further the remote control lever to regulate the power of engine in a normal operating condition of such engine, whereas for remotely disengaging the clutch fuel supply to the engine is firstly reduced by displacing the remote control lever toward the neutral position to bring the engine idling and then the clutch becomes disengaged under an idling condition of the engine by displacing further the remote control lever toward the neutral position.
An example of clutches of the described type and operating means therefor are disclosed in U.S. Pat. No. 3,269,497. The clutch itself disclosed in this U.S. Patent is fashioned such that it comprises cone-shaped first and second friction surfaces formed respectively to first and second clutch members, which are integral with first and second gears located at the driving side of clutch, and a pair of cone-shaped friction surfaces which are formed to a movable clutch member mounted on a rotatable shaft by a helical spline or steep pitch screw thread connection at a location between the first and second gears. Once one of the pair of friction surfaces has become in contact with one of the first and second friction surfaces, the movable clutch member is forced to displace into a direction of enlarging the clutch engaging force by free-wheel action caused by the torque. This clutch disclosed in U.S. Pat. No. 3,269,497 is also remote-controlled. Clutch engaging and disengaging means which is directly associated to such clutch and is operated by a remote control system through push-pull control means comprises a wedge-shaped shifting pin which is received by a peripheral V-shaped groove on the above mentioned movable clutch member. The V-shaped groove is particularly fashioned such that center of such groove is eccentric to the common axis of the movable clutch member and rotatable shaft mounting the movable clutch member. The shifting pin is slidably mounted in a control shaft, which is operated to rotate by a control lever projected radially from such control shaft, at an eccentric location of the control shaft and is forced to slide toward the V-shaped groove by a spring. Consequently, when the control lever is rotated by push-pull control means to cause a rotation of the control shaft into one or another direction, the shifting pin becomes displaced from its neutral position toward one or another direction to push the clutch member into a clutch-engaged position. In an engaged state of the clutch, the shifting pin slides to and fro due to eccentricity of the V-shaped groove. The mentioned control shaft is supported by a sleeve so that it may somewhat move toward and away from the movable clutch member. Between the control shaft and the sleeve is disposed a cam mechanism for limiting retreatment of the control shaft. When the control shaft is rotated toward its neutral position, the control shaft is somewhat advanced toward the movable clutch member by such cam mechanism and enlarges the spring force for biasing the shifting pin which is displaced toward its central position in the V-shaped groove by a rotation of the control shaft toward the neutral position due to the eccentric mounting in such control shaft. At the same time, the shifting pin is restrained from moving away from the movable clutch member. Under such condition, the shifting pin rides step by step up on one side of the eccentric V-shaped groove to cause a displacement of the movable clutch member toward a clutch disengaging direction.
This clutch engaging and disengaging means according to U.S. Pat. No. 3,269,497 is such in that particular considerations are taken on the operating mechanism which are located within a housing for the clutch. The wedge-shaped shifting pin employed in this clutch engaging and disengaging means is in contact with the movable clutch member along a line, since such shifting pin is mounted in the control shaft at an eccentric location of such shaft and engages to the movable clutch member at a side of the V-shaped groove which is eccentric to the axis of the clutch. Further, this clutch engaging and disengaging means has no freedom or play in the direction of engaging the clutch because displacement of the control lever toward the direction of engaging the clutch is limited or restrained by the mentioned cam mechanism.
Another example of clutches of the type set forth at the beginning is such that is disclosed in, for example, British Pat. No. 1,266,840 and U.S. Pat. No. 3,176,811. A clutch of this kind comprises a plurality of friction disks of one kind and a plurality of friction disks of another kind. Both kinds of friction disks are arranged alternately. A rotatable plate which is displaced along the axis of the clutch so as to push the friction disks for engaging the clutch is pushed toward the friction disks through a series of balls which are in contact with such rotatable plate at a series of circumferentially extending ramp faces and ride up on such ramp faces for pushing the rotatable plate. Once the clutch has been engaged, the torque transmitted by the clutch acts to ride the balls up further on the ramp faces thereby pressure against the friction disks and, therefore, clutch engaging force being enlarged. That is, a servo-action is caused. In general, a clutch of this kind is engaged and disengaged by means of shifting sleeve which is disposed around the rotatable plate. Such shifting sleeve is displaced along the axial direction so as to displace the rotatable plate through the balls. The shifting sleeve is displaced by, in general, a remote control.
Preferably, an engaging and disengaging means which is associated directly to a remote-controlled clutch of the type detailed hereinbefore will reduce the clutch operating force or load on one hand. But, on the other hand, it is preferred that such clutch engaging and disengaging means will provide a pressure or force directing toward a direction of engaging the clutch to the movable clutch member still in an engaged state of the clutch and also will prevent with certainty an unexpected engagement of the clutch in the disengaged state of the clutch. That is, it is likely that a spontaneous disengagement of the clutch will not be caused because the movable clutch member is forced in an engaged state of the clutch by the torque to displace toward a direction of engaging the clutch. Such spontaneous or unexpected disengagement of the clutch may, however, be caused, for example, in such a case where, in a marine propulsion device in which a clutch of this type is interposed between an engine and propeller, power or rotation of the engine is suddenly reduced during a sailing. This is because, in such a case, a reaction force is applied to the propeller from water due to the inertia of such propeller so that the clutch or the engaged portion thereof may be applied with a torque from the side of the propeller which torque may be larger than that transmitted from the side of the engine. Further, because a clutch engagement is enhanced automatically by the torque in a clutch of this type, when an unexpected contact between engageable clutch members is caused the clutch will become engaged by the torque transmitted to the driving side of clutch. Such unexpected engagement of the clutch is dangerous and should be avoided with certainty. Furthermore, it is preferred that abrasion of clutch operating members will be prevented as much as possible. For this, engagement between two movable clutch operating members which are displaced together due to such engagement is preferably such in that the two members are in engagement to one another with surfaces thereof.
A remote control system may have, of course, a manufacturing error or tolerance. Abrasion due to use is, of course, caused on the engageable clutch members and the like. It is thus preferred that a clutch engaging and disengaging means may absorb or swallow such manufacturing error and/or clearance due to such abrasion. It is further preferred that a clutch operating means permits an easy adjustment and maintenance thereof. Such means is preferred, of course, to be simple in structure.
The present invention aims to provide a novel clutch engaging and disengaging means of the type set forth at the beginning which satisfies as much as possible the demands detailed above.